Understanding Material Properties and Classifications: Metals and Alloys

Understanding Material Properties and Classifications

A material is any substance used for the construction of an object. Raw materials are those funds derived from nature in order to use them in any subsequent process of production. The evolution of materials is due to technological progress.

Properties

Properties may be classified as electromagnetic, thermal, chemical, and optical. The mechanical properties are the most important. The main ones are:

• Hardness: The resistance of a material to being pierced or scratched by another.
• Tenacity: The ability of a material not to deform or break when a force is applied.
• Plasticity: The ability of a material to deform under the action of a force and retain the new shape.
• Elasticity: The ability of a material to recover its original shape.
• Ductility: The ability of a material to undergo large deformations without breaking when cold.
• Malleability: The ability of a material to undergo plastic deformation without rupture.

Classification

Materials can be classified by origin:

• Mineral (metals and alloys, plastics)
• Biological (plant, animal)
• Synthetic (polymers, nanotechnology, electrical, silicones, intelligent hybrids)

Metals and Alloys

If the material consists of a single chemical element, it is a pure metallic material. If it is formed by more than one chemical element, it is an alloy.

Pure Metals

To isolate them from the minerals that contain them, complex transformation processes are needed, involving high power consumption and high economic costs.

Properties:

• High hardness
• Can be worked through casting processes
• Good conductors of heat and electricity
• Strength allows for use in architectural and structural applications under high stress
• Easily recyclable

The main problem for the use of metals is their tendency to corrode. Except for gold and silver, the others are exposed to damage caused by the attack of atmospheric oxygen.

Copper: Was the first of the pure metals to be used by humans. Its properties are: ability to conduct electricity, non-metallic, easy to work, malleable, ductile, and soft. It accepts soldering and heat treatment.

Iron: Is the most used metal today. It is a heavy metal with high strength and ductility (used in manufactured structures). Its magnetic properties are notable (used in the construction of magnets). It is likely to corrode. Therefore, in many cases, it is preferable to use alloys such as steel or apply protective treatments such as coverage with antioxidant paints.

Aluminum: Lighter than the rest of the metals, a good conductor of heat and electricity, malleable, ductile, and softer than copper. It supports the application of welding, casting, and forging processes. It is one of the metals with the highest number of applications.

Silver and Gold: Silver is a very ductile and malleable metal. It is the best conductor of electricity and heat. It is also used in the manufacture of mirrors. Gold is the most ductile and malleable metal. It is a high-density, good conductor of heat and electricity. It is used in jewelry and to cover and protect valuable items from the sun.

Alloys

An alloy is a combination of various metals, which can also include small amounts of some non-metallic elements. They are usually classified into:

Ferroalloys: The main ferroalloy is steel, obtained by adding less than 2% carbon to iron. Steels without other elements are known as carbon steels. Nearly 90% of the steels used in industry are carbon steels, where the proportion of carbon is kept below 1%.